Typical catheter assemblies incorporate one of two types of needle protection mechanisms. An active system is a needle protection mechanism that requires a separate user action to initiate needle protection, such as depression of an activation button to activate automatic and instantaneous needle retraction into a barrel assembly. This action would take place after the needle is withdrawn from a skin of a patient and from the catheter. On the other hand, a passive system is a needle protection mechanism that automatically protects the needle when a user manually retracts the needle from the catheter, typically using a spring clip and without requiring a separate user action. In other words, the needle is immediately protected when it is withdrawn from a skin of a patient and from the catheter.
Various disadvantages arise in each of the needle protection mechanisms. Specifically, in active systems, the user may neglect to depress the activation button or fail to perform the secondary user action to protect the needle. For example, when the activation button is not depressed, the used needle tip that is covered in blood is undesirably exposed from the body of a patient. In passive systems, the spring clip includes undesirable sharp edges, blood is exposed on the needle and the spring clip, and the spring clip can be manually manipulated to expose the distal tip of the needle after it is covered.
There are also various means of damping the speed of needle retraction into the barrel assembly of the catheter assembly. Some damping mechanisms include a silicone gel, an O-ring and a silicone washer. However, these damping mechanisms are not always able to adequately control the retraction speed of the needle.